In this study, investigators will determine in humans with advanced HIV disease: (1) the safety profile of sublethal conditioning with total lymphoid irradiation and cyclophosphamide; (2) the safety profile of transplanting baboon bone marrow enriched for facilitator and stem cells; (3) if this sublethal conditioning, when used in conjunction with the facilitator cell method, is sufficient to achieve engraftment of baboon bone marrow stem cells; (4) in a preliminary manner, whether immune reconstitution with baboon derived bone marrow stem cells can be achieved; (5) in a preliminary manner which baboon derived viruses, if any, are transferred as a result of the transplant.